GASPING CENTER. The location and function of the gasp mechanism will be studied in rats and cats. The muscle groups involved in normal respiraton and gasping will be compared. The central neurons responsible for gasping will be sought and compared to the function of neurons involved in eupnea. The effects on both types (if there are separate neurons for both functions) of hypoxia, hypercapnea, and cord transection will be determined, and the effects of chronic hypoxia. APNEA INTERRUPTION. Primary apnea will be induced by nasal occlusion in infant monkeys during spontaneous quiet sleep and active sleep. The ability to resume normal respiration after removal of the stimulus will be determined with maturation, and with acute and chronic hypoxia, and during pharmacologic intervention.